inventory.insertNewItem bug? (aka Yahwho noob)

This is confusing me a little. So I hope it's a bug that can be squashed. . . (or me doing it wrong )

Inventory inventory = player.getInventory();
inventory.insertNewItem(itemID, variation, 1, playerInventorySlot, slotType );

When this code is called the first time, I get 1 of the items added to players inventory and message saying 1 added - all good.

The second time I call it I get 2 added to the inventory and a messages saying 3 added

The third time I call it I get 3 added to the inventory and a messages saying 6 added

The fourth time I call it I get 4 added to the inventory and a messages saying 10 added

The fifth time I call it I get 5 added to the inventory and a messages saying 15 added

The sixth time I call it I get 6 added to the inventory and a messages saying 21 added

The seventh time I call it I get 7 added to the inventory and a messages saying 28 added

I've also tried:

Inventory inventory = player.getInventory();
inventory.insertNewItem( itemID, variation, 1)

This still results in weird behaviour.

(I put a literal 1 int in to make sure it wasn't my cache file spewing out garbage.)

p.s. I know pnb works so I'm even more confused

if ( event.getGuiElement() == confirm ){




Inventory inventory = player.getInventory();
inventory.insertNewItem(itemID, variation, 1);




}

Haha I think I know what the problem might be. . .

When a player initialises a popup I register a new event listener. I *think* I need to somehow kill the event listener once it's been used.

I'm looking now, but do you know if there is something like "unregisterEventListenter(this);" ?

I was calling this.destroy(); but it may not be killing the event listener? I dunno. lol

Update: Yes it was because I was not unregistering my event listener after working with it all fixed.

Is registering and unregistering an expensive operation?

Awkward is my middle name